Chemical Pathology MCQs: Clinical Chemistry, OmpathStudy

Chemical Pathology MCQs — Part 1 Topic: General Clinical Chemistry This section covers routine biochemistry panels, electrolytes, and basic diagnostic tests used in everyday clinical chemistry practice. Q1. Which of the following is NOT measured in a basic metabolic panel (BMP)? A) Glucose B) Creatinine C) Bilirubin D) Sodium Answer: C) Bilirubin Explanation: A BMP includes glucose, electrolytes, BUN, and creatinine; bilirubin is part of liver function tests, not the BMP. Q2. Which test is the most specific for liver function? A) ALT B) AST C) ALP D) GGT Answer: A) ALT Explanation: ALT is more liver-specific than AST, which is also found in heart, muscle, and other tissues. Q3. Which electrolyte is the most abundant cation in extracellular fluid? A) Sodium B) Potassium C) Calcium D) Magnesium Answer: A) Sodium Explanation: Sodium is the primary extracellular cation and main determinant of plasma osmolality. Q4. An increased anion gap metabolic acidosis can be caused by: A) Diarrhea B) Lactic acidosis C) Renal tubular acidosis D) Hyperaldosteronism Answer: B) Lactic acidosis Explanation: Lactic acid accumulation adds unmeasured anions, raising the gap; the others cause normal anion gap acidosis or alkalosis. Q5. Which analyte is most useful in the diagnosis of multiple myeloma? A) Serum iron B) Beta-2 microglobulin C) Serum protein electrophoresis D) Alkaline phosphatase Answer: C) Serum protein electrophoresis Explanation: SPEP detects the monoclonal (M) protein spike characteristic of myeloma. Topic: Endocrine Disorders & Hormone Assays This section tests knowledge of hormone physiology and lab tests used to diagnose common endocrine diseases. Q6. Which of the following is an adrenal hormone? A) T3 B) Cortisol C) Prolactin D) ADH Answer: B) Cortisol Explanation: Cortisol is produced by the adrenal cortex; the others come from the thyroid, pituitary, or hypothalamus/posterior pituitary. Q7. In primary hypothyroidism, TSH levels are typically: A) High B) Low C) Normal D) Undetectable Answer: A) High Explanation: A failing thyroid gland leads to low T4, triggering compensatory pituitary TSH elevation via loss of negative feedback. Q8. Which hormone is most useful for diagnosing acromegaly? A) Cortisol B) Growth hormone C) IGF-1 D) ACTH Answer: C) IGF-1 Explanation: IGF-1 reflects average GH secretion over time and is more stable than pulsatile GH itself. Q9. Which test is used to confirm Cushing's syndrome? A) Serum cortisol at 8 AM B) Low-dose dexamethasone suppression test C) Serum ACTH D) 24-hour urine free cortisol Answer: B) Low-dose dexamethasone suppression test Explanation: Failure to suppress cortisol after low-dose dexamethasone confirms autonomous cortisol excess. Q10. Which enzyme deficiency is most common in congenital adrenal hyperplasia? A) 21-hydroxylase B) 17-hydroxylase C) 11β-hydroxylase D) 5α-reductase Answer: A) 21-hydroxylase Explanation: 21-hydroxylase deficiency accounts for over 90% of CAH cases, causing impaired cortisol/aldosterone synthesis and androgen excess. Topic: Kidney Function & Electrolytes This section covers renal filtration markers, electrolyte disturbances, and acid-base consequences of kidney disease. Q11. The best marker for glomerular filtration rate (GFR) is: A) Serum creatinine B) Blood urea nitrogen (BUN) C) Creatinine clearance D) Serum cystatin C Answer: D) Serum cystatin C Explanation: Cystatin C is less affected by muscle mass, diet, and age than creatinine, making it a more accurate GFR marker. Q12. A low fractional excretion of sodium (FENa) suggests: A) Acute tubular necrosis B) Prerenal azotemia C) Hyperkalemia D) Hypocalcemia Answer: B) Prerenal azotemia Explanation: Intact tubules avidly reabsorb sodium in response to reduced renal perfusion, giving FENa <1%. Q13. Which electrolyte abnormality is associated with ECG changes such as peaked T waves? A) Hypocalcemia B) Hyperkalemia C) Hypernatremia D) Hypomagnesemia Answer: B) Hyperkalemia Explanation: Elevated potassium alters myocardial repolarization, producing peaked T waves and risking arrhythmia. Q14. Which acid-base disorder is commonly seen in patients with chronic kidney disease? A) Metabolic acidosis B) Metabolic alkalosis C) Respiratory acidosis D) Respiratory alkalosis Answer: A) Metabolic acidosis Explanation: Failing kidneys cannot excrete acid or regenerate bicarbonate, leading to chronic metabolic acidosis. Q15. Which of the following conditions leads to an increased BUN-to-creatinine ratio? A) Liver failure B) SIADH C) Prerenal azotemia D) Rhabdomyolysis Answer: C) Prerenal azotemia Explanation: Reduced renal perfusion increases passive urea reabsorption disproportionately to creatinine, raising the ratio above 20:1. Topic: Liver Function & Lipid Metabolism This section covers liver enzymes, lipoproteins, and glucose interpretation. Q16. Which liver enzyme is most specific for hepatocellular injury? A) ALP B) AST C) ALT D) GGT Answer: C) ALT Explanation: ALT is found predominantly in the li